Trailers, motor homes, and like vehicles have become very popular. These types of vehicles have a floor level elevated at a considerable distance above ground level. This makes stairs or some other transitional surface necessary.
There is a variety of existing stair designs for these types of vehicles. Some stairs have fixed steps and are deployed by placing the stairs adjacent to the vehicle when it is parked; however, these fixed stairs must be placed into a storage space when the vehicle is traveling. Others stair assemblies are retractable. Retractable stairs can be extended to a deployed position that provides a transitional surface out of the vehicle and then retracted out of way when not in use.
FIGS. 1 and 2 illustrate an existing retractable stair assembly 10 for a trailer 12. The retractable stair assembly 10 is movable between a deployed position (FIG. 1) and a stowed position (FIG. 2). As is typical, the retractable stair assembly 10 is installed underneath the trailer 12. Unfortunately, in this position, the retractable stair assembly 10 is exposed to the elements, such as rain, snow, road salt and/or dirt. Additionally, the retractable stair assembly 10 is vulnerable to being damaged, such as due to lack of clearance underneath the trailer 12 on a steep slope or rocks kicking up underneath the trailer 12 as it travels.
When the retractable stair assembly 10 is deployed, there is a slide assembly 14 that moves the steps 16 and step platform 18 (the first step down from the floor level of the trailer) out from its stowed position underneath the trailer 12. The floor level of the trailer 12 is represented by line 13.
Since the retractable stair assembly 10 is stowed underneath the trailer 12, the retractable stair assembly 10 includes a lift mechanism 20 to elevate the step platform 18 as the retractable stair assembly 10 is being deployed. When in the stowed position, the step platform 18 collapses downward to align with the slide assembly 14 underneath the trailer 12; however, when the step platform 18 is deployed, it elevates via the lift mechanism 20. Without this lift mechanism 20, the step platform 18 would be positioned too low from the floor level 13 and would be a potentially dangerous transition.
The step platform's 18 elevated height in the deployed position (FIG. 1) compared to the collapsed position (FIG. 2) is illustrated by comparing the longitudinal axis of the slide assembly 14 (defined by line 22) with the longitudinal axis of the step platform 18 (defined by line 24) in the deployed position. The lift mechanism 20 and elevation of the step platform 18 during deployment increases complexity and manufacturing cost of the retractable stair assembly 10. Moreover, this design necessitates a fixed length of the step platform 18 that cannot be adjusted.
As seen in FIG. 2, the retractable stair assembly 10 is underneath the trailer frame structure 26. As discussed above, this placement of the retractable stair assembly 10 has several downsides, including exposure to the elements and vulnerability to being damaged. Additionally, as discussed, this position underneath the trailer requires the lift mechanism 20 to elevate the step platform 18 during deployment so the first step out of the trailer 12 is not down too far, which would be potentially dangerous.
Therefore, a need exists that overcomes one or more of the disadvantages of present retractable stair assemblies.